The Motor System

Question 1

the lower motor neuron is responsible for

Answer 1

muscle contraction

Question 2

lower: where are cells localized?

Answer 2

ventral horn of the spinal cord

Question 3

lower: axons leave through the

Answer 3

ventral root

Question 4

lower: it is the ( ) for all motor outflow

Answer 4

final common pathway

Question 5

lower: uses ( ) at the NMJ

Answer 5

ACh

Question 6

lower or upper lesion: flaccid paralysis

Answer 6

lower

Question 7

lower or upper lesion: HYPOrelfexia and HYPOtonia

Answer 7

lower

Question 8

lower or upper lesion: spontaneous, uncoordinated muscle fiber contraction (fasciculation)

Answer 8

lower

Question 9

lower or upper lesion: muscle atrophy

Answer 9

lower

Question 10

do lower or upper directly innervate muscle?

Answer 10

lower only!

Question 11

upper motor neuron is responsible for:

Answer 11

termination and modification of responses and reflexes

Question 12

upper localized in ( )

Answer 12

brain

Question 13

upper axons located where?

Answer 13

descending motor tracts

Question 14

lower or upper: act by fascilitating or inhibiting activity of lower motor neurons

Answer 14

upper

Question 15

lower or upper lesion: spastic paralysis (muscle rigidity)

Answer 15

upper

Question 16

lower or upper lesion: HYPERreflexia, HYPERtonia

Answer 16

upper

Question 17

lower or upper lesion: no muscle atrophy

Answer 17

upper

Question 18

gray matter is composed of

Answer 18

cell bodies

Question 19

where are motor neurons located in the spinal cord?

Answer 19

the ventral horn

Question 20

what are the 2 types of motor neurons?

Answer 20

1) alpha motor neurons

2) gamma motor neurons

Question 21

motor neuron: innervate normal (extrafusal) muscle fibers

Answer 21

aplha motor neurons

Question 22

motor neuron: synonymous with lower motor in that it innervates muscle

Answer 22

alpha motor neurons

Question 23

a motor unit is defined as

Answer 23

an aplha motor neuron plus all the muscle fibers that it innervates

Question 24

motor neuron: innervated muscle spindle (intrafusal) fibers

Answer 24

gamma motor neurons

Question 25

where are interneurons present?

Answer 25

in all areas of the gray matter

Question 26

integrate info and participate in reflexes

Answer 26

interneurons

Question 27

the awareness of posture and movement

Answer 27

proprioception

Question 28

what sensors are involved in proprioception?

Answer 28

muscle spindle organs and golgi tendon organs

Question 29

muscle spindle organs afferent: the primary nerve fibers ends in ( ) around the nuclear bag cell

Answer 29

annulospiral

Question 30

muscle spindle organ that stimulated by stretch

Answer 30

annulospiral

Question 31

muscle spindle organ afferent: phasic

Answer 31

annulospiral

Question 32

muscle spindle organ afferent: tonic

Answer 32

flower-spray

Question 33

the secondary nerve fiber ends in ( ) endings on the intrafusal fibers (nuclear chain fibers)

Answer 33

flower-spray

Question 34

the bag and intrafusal fibers are all encased in what?

Answer 34

connective tissue sheath

Question 35

the entire organ, within the sheath, is surrounded by what?

Answer 35

normal extrafusal muscle fibers

Question 36

muscle spindle organ efferent: innervate the extrafusal muscle fibers

Answer 36

alpha motor nerve fibers

Question 37

muscle spindle organ efferent: innervate the intrafusal muscle fibers

Answer 37

gamma nerve fibers

Question 38

gamma motor neurons contract the intrafusal fibers, thus recovering the ( ) that is lost when the muscle contracts

Answer 38

sensitivity

Question 39

knee jerk reflex is an example of what type of reflex? why?

Answer 39

negative feedback; stretching the muscle causes the muscle to contract

Question 40

do knee jerk reflexes go through interneurons or are they monosynaptic?

Answer 40

monosynaptic

Question 41

monosynaptic knee jerk reflex: muscle spindle sensory neurons synapse directly onto

Answer 41

the alpha motor neuron

Question 42

in many reflexes, the sensory neuron that stimulates the motor neuron of a muscl also inhibits the antagonist muscle

Answer 42

reciprocal innervation

Question 43

a reflex involving opposing behaviors on either side of the body designed to avoid an upleasant stimulus while maintaining balance

Answer 43

crossed extensor reflex

Question 44

relaxation of extensor and contraction of flexors; contraction of extensors, relations of flexors

Answer 44

double reciprocal innervation/crossed extensor reflex

Question 45

glolge tendon organ is located where?

Answer 45

tendons

Question 46

is golgi tendon monosynaptic or disynaptic?

Answer 46

disynaptic

Question 47

the ( ) is stimulated when the muscle is stretched

Answer 47

spindle

Question 48

the ( ) is stimulated when the muscle is contracted

Answer 48

golgi

Question 49

frontal love contains what

Answer 49

the motor cortex, premotor cortex, and areas involved in planning of behavior

Question 50

lies at the division of the frontal and parietal lobes and the motor cortex is on the precentral gyrus

Answer 50

central sulcus

Question 51

pre/postcentral: more motor

Answer 51

pre

Question 52

motor man and sensory man mostly has

Answer 52

hands, face, mouth

Question 53

the majority of the fibers of the pyramidal tract originate from the

Answer 53

primary motor cortex (but some from secondary or other cortical areas)

Question 54

the majority of fibers (90%) contralateral or ipsilateral?

Answer 54

contralateral

Question 55

pyramidal tract: contralateral form what tracts?

Answer 55

lateral corticospinal tracts

Question 56

pyramidal tract: ipsilateral form what tracts?

Answer 56

anterior corticospinal tracts

Question 57

Babinski can be used to detect what?

Answer 57

pyramidal tract damage

Question 58

descending fiber tract: from red nucleus

Answer 58

Rubrospinal tract

Question 59

descending fiber tract: from vestibular nucleus

Answer 59

vestibulospinal tract

Question 60

descending fiber tract: from reticular formation

Answer 60

reticulospinal tract

Question 61

brainstem has a lot of lesser thought about functions such as

Answer 61

respiration, cardiovascular system, GI, equilibrium, and eye movements

Question 62

what 3 pairs of peduncles connect cerebellum to brain?

Answer 62

inferior, middle, superior

Question 63

the cerebellum is only ( )% of brain weight but contains over half of the neurons

Answer 63

10%

Question 64

cerebellum function: ( ) the planning of limb movements

Answer 64

coordinates

Question 65

cerebellum function: ( ) movements as they are performed

Answer 65

modifies

Question 66

cerebellum function: corrects errors for ( )

Answer 66

overshooting or undershooting

Question 67

cerebellum function: what can cause uncoordinated behavior similar to being intoxicated

Answer 67

lesions

Question 68

motor cortex has humonculus. What also has one?

Answer 68

cerebellum

Question 69

cerebellum receive inputs from where?

Answer 69

- frontal motor and parietal cortex through the pons - inferior olive through the motor cortex and red nucleus - vestibular nucleus and spinal cord

Question 70

the only output from cerebellar processing and innervates cells in the deep cerebellar nuclei

Answer 70

purkinje cell

Question 71

the neurons in the deep cerebellar nuclei primarily innervate cells in the ( ) which then go to the motor and premotor cortex

Answer 71

thalamus

Question 72

are there descending tracts from the cerebellum?

Answer 72

no

Question 73

basal ganglia are deep within what?

Answer 73

white matter or the cerebrum

Question 74

plays a crucial role in initiating and terminating movements

Answer 74

basal ganglia

Question 75

dysfunction of basal ganglia can lead to what?

Answer 75

chorea (uncontrolled movements) and Parkinson's disease (hard time initiating movement)

Question 76

input and output from basal ganglis

Answer 76

- input: several areas of cortex | - output: thalamus --> premotor cortex

Question 77

what is the main mechanism of basal ganglion modulation of movements

Answer 77

disinhibition of thalamocortical neurons (disinhibit thalamus, which stimulates cortex)